1. Technical Field
The present invention relates to a valve assembly for controlling the flow of fluids through a medical device, and more particularly, to a hemostatic valve assembly incorporating an iris valve for controlling fluid flow.
2. Background Information
A variety of well-known medical procedures are initiated by introducing an interventional device such as a catheter, trocar, sheath, and the like into a vessel in a patient's body. Typical procedures for introducing an interventional device into a blood vessel include the well-known Seldinger technique. In the Seldinger technique, a needle is injected into a blood vessel, and a wire guide is inserted into the vessel through a bore of the needle. The needle is withdrawn, and a dilator is inserted over the wire guide. The dilator is typically located inside an introducer sheath which is also inserted into the vessel. The introducer sheath typically includes a hemostatic valve, through which the dilator passes. Following proper placement of the introducer sheath, the dilator is removed. The interventional device may then be inserted through the sheath and hemostatic valve into the vessel.
As the interventional device is introduced into the vessel, care must be taken to avoid the undesirable introduction or leakage of air into the vessel. Similarly, care must be taken to avoid the undesirable leakage of blood or other bodily fluids, or a cavity-pressurizing gas from the patient. As procedures for introducing catheters and other interventional devices have become more widely accepted, the procedures associated with their use have become more diverse, and the variety of sizes and types of such introducer devices has grown dramatically. As a result, the risk of inward or outward leakage of fluids has increased, along with the necessity to maintain vigilance to minimize the possibility of such leakage.
One known way to minimize leakage is to provide one or more disk-like gaskets in an elongated passageway of a device through which fluids may be controllably passed into or out of the body. Such disks have opposing surfaces and often include one or more slits that extend partially across each of the surfaces and inwardly toward the interior of the disk. A generally axial opening is provided between the slits to provide a sealable path for insertion of an interventional device through the disks. Examples of such disks are described, e.g., in U.S. Pat. Nos. 5,006,113 and 6,416,499, incorporated by reference herein. These disks are generally effective for sealing large diameter devices, but may be less effective for sealing smaller diameter devices. This may be especially true when a smaller diameter device is introduced through a disk following the earlier passage of a larger diameter device.
Another type of valve that is presently used for sealing elongated passages in a medical device to prevent passage of fluids is commonly referred to as an iris valve. Iris valves are described, e.g., in U.S. Pat. Nos. 5,158,553 and 7,172,580, incorporated by reference herein. An iris valve may comprise a valve hub that is joined to a catheter-type device, and a knob that is rotatably engaged with the hub. An elastomeric sleeve having an elongated passageway therethrough is positioned in an opening through the interior of the valve body. The opposing axial ends of the elastomeric sleeve are joined to the hub and the rotatable knob, respectively. When the rotatable knob is rotated in a first direction, the passageway of the elastomeric sleeve is fully opened. When the knob is rotated in a second direction opposite the first direction, the elastomeric sleeve is twisted intermediate the two ends to effect closure of all or part of the elongated passageway.
Although the prior art iris valves are generally effective for sealing sheaths of certain sizes and compositions, such valves have certain shortcomings. For example, the manner of engaging the ends of the valve of the '553 patent to the respective hub and knob is less than optimal. Such ends are capable of disengagement, which destroys the ability of the valve to form a seal. In addition, the outer housing of the valve is not easily grasped by the physician during use.
The valve of the '580 patent has been found to be generally effective in many applications. This valve may include longitudinal grooves and corresponding ridges that cooperate during rotation of the knob relative to the hub to provide feedback to the physician of the amount of closure of the valve. The particular design of the valve is believed to have sufficient flex in the respective valve parts to enable the knob to be easily rotated relative to the hub. However, the outer contour of this valve is generally cylindrical, and does not provide an ergonomic surface that provides for optimal manipulation by the physician.
It would be desirable to provide a valve assembly that overcomes the problems associated with prior art iris valves.